The contractor shall supply all necessary equipment, personnel, and facilities to conduct a large scale in vivo screening program in accordance with the protocols as set forth in Cancer Chemotherapy Reports, dated September 1972, Vol. 3, No.2, Part 3. Drug screening in vivo will include the evaluation of synthesis materials and materials derived from natural sources (plants, soil fermentation, animals) for therapeutic activity against tumors in rodents. In vivo assay (host-tumor) systems, experimental protocols for testing, parameters and criteria for evaluating biological activity of test materials, methods of reporting results, and quality specifications for testing are specified in Exhibit I. Assay systems and test materials will be assigned and supplied by NCI. Animals will be supplied by NCI. Tumors will be supplied by NCI and will be maintained in vivo as stock tumors by the contractor.